Packaging methods
Packaging method. The method includes providing a conductive substrate comprising top and bottom surfaces, forming a first circuit layer of a package substrate and then packaging an active device overlying the top surface, and forming other circuit layers and a contact pad of the package substrate overlying the bottom surface.
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1. Field of the Invention
The invention relates to package technology and in particular to integration of fabrication methods of layered leadframes and encapsulating processes.
2. Description of the Related Art
Due to the demand for high-frequency, high-speed system-in-package (SIP), a small-aspect package design capable of effective heat dissipation and excellent electrical performance is necessary. Thus, package technology is a critical issue in SIP design. QFN (quad flat no-lead), capable of low pin inductance, is a widely anticipated technology, which utilizes a lead frame as a substrate.
A lead frame for QFN has a die paddle, attaching a chip thereto, and a plurality of leads beyond the die paddle. The chip has a plurality of terminals respectively electrically connecting the corresponding leads. An encapsulant covers the chip and respectively exposes the ends of the leads. The lead ends and the encapsulant are approximately coplanar, achieving a QFN package.
A QFN package has smaller aspect and better electrical performance than other package types. In a printed circuit board assembly (PBCA) process, QFN packages and passive devices are individually disposed on a PCB, resulting in the necessity to design PCB wirings to electrically connect corresponding QFN packages and passive devices. The required wirings may enlarge the PCB and/or wiring density thereof, which may cause crosstalk therebetween.
BRIEF SUMMARY OF THE INVENTIONPackaging methods are provided.
The invention provides a packaging method. First, a conductive substrate comprising a top surface and bottom surface is provided. A base embryo and a first wiring pattern layer are then formed beyond the base embryo overlying the top surface of the conductive substrate. Next, an active device is electrically connected to the first wiring pattern layer. Next, an encapsulant is formed overlying the top surface of the conductive substrate, encapsulating the active device and the first wiring pattern layer. Next, the conductive substrate between the base embryo and the first wiring pattern layer is removed. The remaining conductive substrate underlying the base embryo becomes part thereof. Parts of the remaining conductive substrate become a conducting device and a pad embryo electrically connecting the first wiring pattern layer. Next, a first dielectric layer is formed among the base embryo, the conducting device, and the pad embryo. Next, the base embryo and pad embryo are thickened, and a second wiring pattern layer is formed overlying the first dielectric layer. Further, a second dielectric layer is formed among the base embryo, the second wiring pattern layer, and the pad embryo. Finally, the base embryo and pad embryo are thickened, respectively acting as an active device base and a pad.
The invention further provides another packaging method. First, a conductive substrate comprising a top surface and bottom surface is provided. A base embryo and a first wiring pattern layer, comprising a plurality of traces, are then formed beyond the base embryo overlying the top surface of the conductive substrate. Next, a passive device is electrically connected between at least two of the traces. Next, an active device is electrically connected to the first wiring pattern layer. Next, an encapsulant is formed overlying the top. surface of the conductive substrate, encapsulating the passive device, the active device, and the first wiring pattern layer. Next, the conductive substrate between the base embryo and the first wiring pattern layer is removed. The remaining conductive substrate underlying the base embryo becomes part thereof. Parts of the remaining conductive substrate become a conducting device and a pad embryo electrically connecting the first wiring pattern layer. Next, a first dielectric layer is formed among the base embryo, the conducting device, and the pad embryo. Next, the base embryo and pad embryo are thickened, and a second wiring pattern layer is formed overlying the first dielectric layer. Further, a second dielectric layer is formed among the base embryo, the second wiring pattern layer, and the pad embryo. Finally, the base embryo and pad embryo are thickened, respectively acting as an active device base and a pad.
Further scope of the applicability of the invention will become apparent from the detailed description given hereinafter. It should be understood, however, that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
A detailed description is given in the following embodiments with reference to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGSThe invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:
The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims.
In
In
A base embryo 120a and a first wiring pattern layer are formed overlying the top surface 100a of the conductive substrate 100 as shown in
In
In
Next, an optional protection layer such as a solder mask can be formed overlying the first wiring pattern layer. The protection layer may be formed overlying the base embryo 120a when an active device is attached by flip chip technology, for example. In this embodiment, formation of the protection layer overlying the first wiring pattern layer is exemplified.
In
In some embodiments, the protection layer is not formed and the first patterned mask layer 111 is removed, followed by attachment of a passive device.
Next, following that shown in
In
In
In
In
Next, the conductive substrate 100 between the base embryo 120a and the first wiring pattern layer is removed from the bottom surface 100b thereof. Note that the step shown in
In
Next, the exposed conductive substrate 100 is removed by a method such as etching utilizing the third patterned mask layer 113 as an etch mask, resulting in the remaining conductive substrate 100 underlying the base embryo 120a acting as parts thereof, and parts of the remaining conductive substrate 100 respectively acting as pad embryos 101a and 103a, and a conducting device 102 electrically connecting the first wiring pattern layer. The conducting device 102 can electrically connect to at least one of the traces 131 through 134 as desired. Alternatively, a plurality of the conducting devices 102 can be formed for respective electrical connection between two or more of the traces 131 through 134. In this embodiment, a conducting device 102 is formed, electrically connecting to the trace 132 not electrically connecting to the passive device 20. In this embodiment, further, the pad embryos 101a and 103a respectively electrically connect the traces 131 and 134 which are at the edges of the package. The third patterned mask layer 113 is then removed as shown in
In
Next, the base embryo 120a and the pad embryos 101a and 103a are thickened, and a second wiring pattern layer electrically connecting the conducting device 102 is formed overlying the first dielectric layer 161. Note that the step shown in
In
In
Next, the base embryo 120a and the pad embryos 101a and 103a are thickened, and thus, the active device base 120 and pads 101 and 103 are complete. Note that the step shown in
In
A third dielectric layer 163 can be optionally formed among the active device base 120 and the pads 101 and 103 for preventing unwanted circuit bridge as shown in
In
In
A base embryo 220a and a first wiring pattern layer are formed overlying the top surface 200a of the conductive substrate 200 as shown in
In
In
Next, an optional protection layer such as a solder mask can be formed overlying the first wiring pattern layer. The protection layer may be formed overlying the base embryo 220a when an active device is attached by flip chip technology, for example. In this embodiment, formation of the protection layer overlying the first wiring pattern layer is exemplified.
In
In some embodiments, the protection layer is not formed and the first patterned mask layer 211 is removed, followed by attachment of an active device.
Next, following that shown in
In
In
Next, an encapsulant 250 is formed overlying the top surface 200a of the conductive substrate 200, encapsulating the active device 40 and the first wiring pattern layer. The encapsulant 250 typically comprises a mixture of thermosetting epoxy and silica fillers, or alternatively, transparent glass and/or transparent epoxy when the active device 40 comprises an optoelectronic device.
Next, the conductive substrate 200 between the base embryo 220a and the first wiring pattern layer is removed from the bottom surface 200b thereof. Note that the subsequently described step is exemplary, and not. intended to limit the scope of the invention. Those skilled in the art will recognize the possibility of using various methods to achieve the removal of the conductive substrate 200 subsequently described.
In
Next, the exposed conductive substrate 200 is removed by a method such as etching utilizing the third patterned mask layer 213 as an etch mask, resulting in the remaining conductive substrate 200 underlying the base embryo 220a acting as parts thereof, and parts of the remaining conductive substrate 200 respectively acting as pad embryos 201a and 203a, and a conducting device 202 electrically connecting the first wiring pattern layer. The conducting device 202 can electrically connect to at least one of the traces 231 through 233 as desired. Alternatively, a plurality of the conducting devices 202 can be formed for respective electrical connection between two or more of the traces 231 through 233. In this embodiment, a conducting device 202 is formed, electrically connecting to the trace 232. Further, the pad embryos 201a and 203a respectively electrically connect the traces 231 and 233 which are at the edges of the package. The third patterned mask layer 213 is then removed as shown in
In
Next, the base embryo 220a and the pad embryos 201a and 203a are thickened, and a second wiring pattern layer electrically connecting the conducting device 202 is formed overlying the first dielectric layer 261. Note that the subsequently described step is exemplary, and not intended to limit the scope of the invention. Those skilled in the art will recognize the possibility of using various methods to achieve the thickening of the base embryo 220a and the pad embryos 201a and 203a and the formation of the second wiring pattern layer as subsequently described.
In
In
Next, the base embryo 220a and the pad embryos 201a and 203a are thickened, and thus, an active device base 220 and pads 201 and 203 are complete. Note that the step shown in
In
A third dielectric layer 263 can be optionally formed among the active device base 220 and the pads 201 and 203 for preventing unwanted circuit bridge as shown in
The efficacy of the inventive packaging methods at providing a conductive substrate as a base, followed by formation of a first wiring layer of a package substrate completion of encapsulation for an active device overlying a top surface of the conductive substrate, and then forming a first wiring layer or more wiring layers and pads overlying a bottom surface of the conductive substrate in order to integrate substrate fabrication and packaging processes, provides reduced process cost, shortened production duration, and improved process yield.
While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.
Claims
1. A packaging method, comprising:
- providing a conductive substrate comprising a top surface and bottom surface;
- forming a base embryo and a first wiring pattern layer beyond the base embryo overlying the top surface of the conductive substrate;
- electrically connecting an active device to the first wiring pattern layer;
- forming an encapsulant overlying the top surface of the conductive substrate, encapsulating the active device and the first wiring pattern layer;
- removing the conductive substrate between the base embryo and the first wiring pattern layer, the remaining conductive substrate underlying the base embryo acting as parts thereof, and parts of the remaining conductive substrate acting as a conducting device and a pad embryo electrically connecting the first wiring pattern layer;
- forming a first dielectric layer among the base embryo, the conducting device, and the pad embryo;
- thickening the base embryo and pad embryo, and forming a second wiring pattern layer overlying the first dielectric layer;
- forming a second dielectric layer among the base embryo, the second wiring pattern layer, and the pad embryo; and
- thickening the base embryo and pad embryo, respectively acting as an active device base and a pad.
2. The method as claimed in claim 1, further comprising forming a third dielectric layer between the active device base and the pad.
3. The method as claimed in claim 1, further comprising, prior to electrically connecting the active device, forming a protection layer overlying the first wiring pattern layer, exposing parts thereof for electrically connecting the active device.
4. The method as claimed in claim 1, wherein the active device and the first wiring pattern layer are electrically connected by wire bonding.
5. The method as claimed in claim 1, further comprising electrically connecting the active device and the base embryo.
6. The method as claimed in claim 1, wherein the active device and the base embryo are electrically connected by wire bonding.
7. A packaging method, comprising:
- providing a conductive substrate comprising a top surface and bottom surface;
- forming a base embryo and a first wiring pattern layer, comprising a plurality of traces, beyond the base embryo overlying the top surface of the conductive substrate;
- electrically connecting a passive device between at least two of the traces;
- electrically connecting an active device to the first wiring pattern layer;
- forming an encapsulant overlying the top surface of the conductive substrate, encapsulating the passive device, the active device, and the first wiring pattern layer;
- removing the conductive substrate between the base embryo and the first wiring pattern layer, the remaining conductive substrate underlying the base embryo acting as parts thereof, and parts of the remaining conductive substrate acting as a conducting device and a pad embryo electrically connecting the first wiring pattern layer;
- forming a first dielectric layer among the base embryo, the conducting device, and the pad embryo;
- thickening the base embryo and pad embryo, and forming a second wiring pattern layer overlying the first dielectric layer;
- forming a second dielectric layer among the base embryo, the second wiring pattern layer, and the pad embryo; and
- thickening the base embryo and pad embryo, respectively acting as an active device base and a pad.
8. The method as claimed in claim 7, further comprising forming a third dielectric layer between the active device base and the pad.
9. The method as claimed in claim 7, further comprising, prior to electrically connecting the passive device, forming a protection layer overlying the first wiring pattern layer, exposing parts thereof for electrically connecting the passive and active devices.
10. The method as claimed in claim 7, wherein the active device and the first wiring pattern layer are electrically connected by wire bonding.
11. The method as claimed in claim 7, further comprising electrically connecting the active device and the base embryo.
12. The method as claimed in claim 11, wherein the active device and the base embryo are electrically connected by wire bonding.
13. The method as claimed in claim 7, wherein the passive device and the traces are electrically connected by surface mount technology.
14. The method as claimed in claim 7, wherein removal of the conductive substrate further comprises removing the conductive substrate between the traces.
15. The method as claimed in claim 7, wherein the conducting device electrically connects one of the traces not electrically connecting the passive device.
Type: Application
Filed: Feb 6, 2006
Publication Date: May 10, 2007
Applicant: AIROHA TECHNOLOGY CORP. (HSINCHU)
Inventor: Chien Lee (Hsinchu County)
Application Number: 11/348,935
International Classification: H01L 21/00 (20060101);